The present invention concerns motor driven actuator control systems and methods whereby empirically characterized actuation operation parameters are subsequently monitored, compared, and computed during real time operation to detect obstacles via adaptive obstacle detection threshold(s) for protection of people and/or equipment.
Prior art for automatically-powered actuator systems implement undesirable increased obstacle-sensing detection thresholds to avoid nuisance tripping caused by uncontrolled operation variables of static, transient, and periodic dynamic load conditions that individually and/or collectively cause significant xe2x80x9cnormalxe2x80x9d load variation. These significant ranges of system disturbance variables added to the nominal variable ranges of operation characteristic of system parameters have necessitated increased obstacle detection thresholds within which the automatic actuation system is required to operate to avoid false obstacle detection. Higher obstacle detection thresholds necessary to accommodate all ranges of anticipated load variables inherently desensitize the system ability to detect initial onset of obstacle detection. Large obstacle detection thresholds also inherently increase minimum system operational parameter disturbances for which obstacle detection is reliably possible without false tripping.
Examples of such relatively static but significantly ranging variable forces during closing an automobile sunroof panel include differential air pressure caused by wind loading, air pressure caused by ventilation fan speed and/or window positions, gravity load varying from level to uphill or downhill orientation, friction and/or lubrication characteristics varying with temperature and/or wear, and the like.
Examples of such relatively transient dynamic but significantly ranging variable forces during closing an automatically controlled automobile sunroof panel include wind gust differential pressure caused by opening or closing another window, ambient wind shift, passing and being passed by another vehicle, and/or turning on vehicle ventilation; change of vehicle uphill/downhill attitude; vehicle acceleration or deceleration; rough or poorly lubricated area on a actuator drive mechanism; friction changing with actuator drive motor speed; bumpy road; and the like.
Examples of such relatively periodic dynamic but significantly ranging variable forces during closing an automatically controlled automobile sunroof panel include repetitive rough gear sector, faulty motor commutation segment, buffeting pressure as caused by steady wind turbulence, and the like. Fluid vortex shedding frequency is proportionate to flow velocity past a discontinuity.
Large-ranging system operation variables necessitate obstacle detection thresholds that inherently necessitate greater operational parameter disturbances by obstacles in order to detect obstruction without nuisance tripping. Larger normal operation disturbance variables inherently require larger obstacle force and/or pinching prior to obstruction detection.
Prior art obstacle detection systems slowly adapt obstacle detection template thresholds over several previous operation cycles resulting in inferior real time response to monitoring actuator load-related parameters that can significantly vary from one actuation to the next. Such threshold detection limit algorithms are primarily based upon a running average template of a fixed number of prior actuation operations with fixed factors and/or terms and/or statistically determined tolerance threshold of ongoing measurement parameters for obstacle detection. Therefore, prior art systems and methods incorporate inherent practical limitations on true and reliable obstacle detection performance including minimum obstacle force sensitivity at detection, minimum detection time, minimum stopping time, and minimum obstacle force at the stopped position.
To improve real time microcontroller algorithm performance of obstacle detection one prior art technique has been to control and/or regulate motor drive speed to slower values to directly enable improvements in minimum obstacle force sensitivity at detection, minimum stopping time, and minimum obstacle force at the stopped position. These improvements are at the tradeoff expense of slower actuator operation and increased system RFI (radio frequency interference) and EMC (electromagnetic compatibility) issues.
National Highway Traffic Safety Administration (NHTSA) Standard 118 contains regulations to assure safe operation of power-operated windows and roof panels. It establishes requirements for power window control systems located on the vehicle exterior and for remote control devices. The purpose of the standard is to reduce the risk of personal injury that could result if a limb catches between a dosing power operated window and its window frame. Standard 118 states that maximum allowable obstacle interference force during an automatic closure is less than 100 Newton onto a solid cylinder having a diameter from 4 millimeters to 200 millimeters.
Certain technical difficulties exist with operation of prior art automatic power window controls. One difficulty is undesirable shutdown of the power window control for causes other than true obstacle detection. Detection of obstacles during startup energization, soft obstacle detection, and hard obstacle detection each present technical challenges requiring multiple simultaneous obstacle detection techniques. Additionally, the gasket area of the window that seals to avoid water seepage into the vehicle presents a difficulty to the design of a power window control, since the window panel encounters significantly different resistance to movement in this region. Operation under varying power supply voltage results in actuator speed variations that result in increased obstacle detection thresholds. Previous methods and systems based upon running measurements and calculations from prior operational parameters are inherently limited by their inability to adapt obstacle detection thresholds in real time.
This invention concerns an improved actuator system that provides faster operation, more sensitive obstacle detection, faster actuator stopping with reduced pinch force, and reduced false obstacle detection all with less costly hardware. This invention has utilization potential for diverse automatic powered actuator applications including positioning of doors, windows, sliding panels, seats, control pedals, steering wheels, aerodynamic controls, hydrodynamic controls, and much more. One exemplary embodiment of primary emphasis for this disclosure concerns an automatic powered actuator as a motor vehicle sunroof panel.
This preferred automotive sunroof system implements redundant non-contact obstacle detection prior to physical contact force by the sunroof. The preferred system employed is an optical coupled transmission-interruption sensing via opposing IR (infrared) emitter and IR detector elements across the pinch zone.
This controller system and method incorporate significant improvements in xe2x80x9csensorlessxe2x80x9d electronic parameter sensing as more reliable means for hard and/or soft obstacle detection during initial energization, full travel, and/or end-of-travel.
Preferred means for position and speed sensing is via sensorless electronic motor current commutation pulse sensing of the drive motor. Motor current commutation pulse counting detection means and counting correction routines provide improved position and speed accuracy.
Improved adaptive methods and systems for obstacle detection thresholds based upon empirical operation performance algorithms and real time operation parameter monitoring replace typical operation template methods of prior art. Memory is eliminated as previously utilized for storing a template or xe2x80x9csignaturexe2x80x9d of pre-measured actuation cycle operating parameter variables for subsequent operation cycle parameter measurement and comparison therewith.
Algorithms and coefficients are empirically predetermined for automatic actuator operating parameters. Such algorithms compensate for various operational variables, including actuation speed as related to supply voltage, by virtue of intelligent software adaptation capability.
Only in certain limited cases is cycle calibration of an individual actuator characteristic required for operation after initial powerup and prior to enabling automatic operation. Such cycle calibration typically involves simply learning the number of incremental encoder pulses from full CLOSED to full OPEN positions as well as learning the present position via one of several known position sensing means. This case enables one controller incorporating multiple software algorithm programs to operate a family of sunroofs by simply learning which sunroof is in the system.
Necessity for controlling and limiting motor drive speed by duty cycle energization, PWM (Pulse Width Modulation), linear drive control, or other speed control means is eliminated due to improved real time algorithms that adapt to full-ranging battery-powered actuation speeds and variable load conditions. Thus, actuation occurs at full speed powered by full battery voltage.
Stored empirical parameter characterizations and algorithms adaptively modify obstacle detection thresholds during an ongoing actuation for improved obstacle detection sensitivity and thresholds resulting in quicker obstacle detection with lower initial force, lower final pinch force and reduced occurrences of false obstacle detection.
At least one internal and/or external FIFO memory and/or RAM (random access memory) is utilized for storing running measured parameters of an ongoing actuation.
At least one internal and/or external FIFO memory and/or RAM is utilized for storing running calculations based upon running measured parameters of an ongoing actuation.
Empirical characterization of actuator operation parameters and algorithms, ongoing sensing measurements of motor operation parameters, FIFO memories, DSP (digital signal processing), adaptive algorithms for obstacle detection, and adaptive software filters collectively enable ongoing adaptive modification of obstacle detection thresholds xe2x80x9con the runxe2x80x9d in real time for improved obstacle detection sensitivity thresholds with reduced occurrences of false obstacle detection.
Utilization of FIFO memory for actuation speed measurement, motor current measurement, and calculations of an ongoing actuation with real time adaptive algorithms enables real time running adaptive compensation of obstacle detection thresholds.